The present invention relates to density-controlled particulate suspensions for foodstuff, cosmetic, pharmaceutical and other uses and their manufacture. More particularly the invention relates to gel beads suitable for dispersing or suspending in various media to provide, or for use in, foodstuffs, cosmetics, pharmaceuticals, nutraceuticals and the like and to the resultant dispersions or suspensions. Still more particularly, but not exclusively, the invention relates to such gel beads which have a visible appearance in relevant media, and especially to gel beads which convey a desired visual appearance such as color, pearlescence, sparkles, reflectivity, opacity or other visual effect to the media or end product formulation. Furthermore, the invention relates to such products and suspensions containing the inventive gel beads.
The invention will be described with particular reference, by way of example, to the formulation of gel beads as a cosmetic or dermatological delivery system having a variety of applications for delivery of topically applied active agents to the skin, to methods of preparing such delivery systems and to cosmetic or dermatological formulations in which the delivery systems may be incorporated. Based upon these disclosures, the use or application of the invention to other products such as foodstuffs or pharmaceuticals will be apparent to those skilled in the art.
Known to the art are many different types of gel beads made from polysaccharides, gelatin, or other suitable bead forming materials are used in gels and emulsions for their decorative effect and for encapsulation or entrapment of active ingredients.
Sweeny, U.S. Pat. No. 4,756,905 discloses a method of treating a surface (application of colored cosmetics to the human body, column 1, lines 10-11) with an active ingredient (encapsulated pigment, column 3, line 2) comprising providing a carrier liquid (e.g. the carrier liquid conventionally employed in a suntan lotion, column 2, line 61); dispersing in the carrier liquid a multiplicity of visible friable beads, each containing active ingredients for treating the surface (addition of microcapsules containing light-stable dyes or pigments, column 2, lines 62-64); and massaging the carrier with beads onto the surface for rupturing the beads and discharging the active ingredient to mark the surface with ruptured beads (light rubbing (as with a finger) will rupture the microcapsules, highlighting or changing the color in the area where the cosmetic was rubbed by exposing the encapsulated pigment within the composition, column 2 line 67 to column 3, line 3.)
Noda, U.S. Pat. No. 5,089,269 discloses a cosmetic composition on an external treatment agent containing microcapsules, with an average particle size of 0.1 to 2000 .mu.m, enclosing a hydrophobic component, wherein the microcapsules are composed of a gelatin film swollen with water.
Karassik, et al, U.S. Pat. No. 5,925,338 discloses a clear antiperspirant or deodorant gel composition which exhibits reduced staining while retaining aesthetic attributes and efficacy. The oil phase comprises about 10 to 25% of the composition and contains a silicone oil and a polyether substituted silicone emulsifying agent. The silicone oil comprises a mixture of a non volatile silicone, preferably a non-volatile linear silicone, and a volatile linear silicone. It has been found that reducing the amount of non-volatile silicone in the known gel composition to a relatively low level (e.g. below about 5%) and adding an amount of volatile linear silicone to the composition (e.g. above about 2%, preferably above about 5%) substantially improves the non-staining properties of the composition.
Ferguson et al. U.S. Pat. No. 6,045,813 discloses surface treatment compositions and methods for skin care and household use. The compositions contain rupturable, or friable beads containing an active ingredient, for example an antiseptic or fragrance. The active ingredient can mark the treated surface with ruptured beads and may be a colorant. The beads employ a diameter and thickness which avoid rupturing during the manufacture of a lotion or gel or the like containing the beads, and after an induction period incubating in the manufactured product are friable when rubbed on to the skin or dispensed through a restrictive orifice.
Delrieu, U.S. Pat. Nos. 5,961,990 and 6,319,507 (“the Delrieu patents”) disclose protective cosmetic particulate gel delivery systems for a topically applied active agent employing an agar gel and a restraining polymer to retain the active agent in the gel. The particles have an average particle diameter of at least 0.05 mm while the restraining polymer has a molecular weight of at least 50,000 daltons and has retention groups to bind the active agent. The restraining polymers can be selected from the group consisting of polyquaternium 24, laurdimonium hydroxyethylcellulose, cocodimonium hydroxyethylcellulose, steardimonium hydroxyethylcellulose, quaternary ammonium substituted water-soluble polysaccharides, alleyl quaternary celluloses and polypeptides having or provided with retention groups to retain the active agent. They are soft enough for to be crushed on the skin without leaving any residue. They are stable in a wide range of pH and in formulations containing high concentrations of surfactants. The delivery system can be incorporated in multiphase cosmetic formulations such as gels, creams and lotions. These gel beads can be used for the decoration of formulas and the delivery of active ingredients.
Relatively large polysaccharide- and gelatin-based beads including, by way of example, some of the preferred embodiments of gel beads disclosed in the Delrieu patents, may be intended to have a distinct visual appearance in the end product. In contrast, the individual presence of smaller particles, such as powders and microspheres, in a given cosmetic formulation may not be detectable by the naked eye, and irregularities in their distribution may not be apparent. However, nonuniform distribution, such as settling or floating of visible beads intended to suspended in a clear liquid and packaged in a clear container is likely to be unattractive and may result in inconsistent delivery of useful ingredients transported in the visible beads.
There is accordingly a need for gel beads and comparable particles, and methods of making them, that can be provided in liquid dispersions with managed distribution of the beads or other particles in liquid media, and in particular for such products and methods that are suitable for cosmetics formulation.
The foregoing description of background art may include insights, discoveries, understandings or disclosures, or associations together of disclosures, that were not known to the relevant art prior to the present invention but which were provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.